1. Field of the Invention
The invention relates generally to insert retention or clamping arrangements. More specifically the invention pertains to a support and clamping blade for a metal cutting insert of a cut-off or parting tool.
2. Description of the Prior Art
Inserts for performing metal cutting operations such as cutting off and grooving are typically held in operative position by relatively narrow support blades which are, in turn, clamped in dove-tailed holders attached to the machine tool. These prior art support blades are typically provided with an elongated slot for locating mating surfaces of the insert whereby the insert cutting edge extends ahead of a leading edge of the support blade. The most pertinent prior patents known to the inventor disclosing such support blades are U.S. Pat. Nos. 3,894,322--Pano, 3,785,021--Norgren, 3,775,818--Sirola, 3,748,710--Lynch, 3,655,969--Pollington et al., and 3,523,349--Pollington et al.
Cut-off tools are also known in the art that feature cams for locking a cutting tool insert in place. The most pertinent prior patents in this area known to the inventor are U.S. Pat. Nos. 2,293,006--Luers, 2,343,855--Luers, 2,223,831--Luers, 1,480,938--Britt, 1,458,973--Bufford, 1,169,594--Amborn, 1,112,185--Amborn, 1,110,281--Amborn, and 1,090,810--Amborn.
In general, the first group of patents listed above teaches use of an insert support blade having an insert locating aperture with clamping performed either by spring biased action of a portion of the blade itself or by use of relatively complex non-unitary clamping actuators operating in conjunction with a sawcut in the blade. Those prior art disclosures with no separate clamp actuators typically rely on cutting forces to hold the insert in operative position. Such an approach can lead to insufficient insert retention capability when such tools are used, for example, in an inverted operating position. The separate clamping actuators disclosed in others of these prior art patents are complex in shape and therefore expensive to manufacture and, additionally, do not typically conform to the narrow thickness dimension of the support blade thereby presenting clearance problems. Another disadvantage found in some of these prior art devices is the necessity for a special tool for inserting or releasing cutting inserts clamped by the support device disclosed.
The second group of patents listed above generally teaches use of cams to effect insert locking in a locating slot in a blade or other type insert holder. However, the disclosed arrangements utilize cams bearing directly on the cutting elements. This approach leads to undesirable forces being exerted directly onto the cam surfaces, which can lead to damaging wear thereof. Additionally, with the disclosed cams, cutting forces on the inserts or blades held by said cams tend to cause reverse actuation of the camming elements used.